1Field of the Invention
The present invention relates to a subrack for housing electronic circuits, in particular in the form of cards or printed circuit boards for telecommunication equipment. The subrack is formed by four crosspieces supplied with means offset by a certain pitch along the axle of each crosspiece for being engaged with corresponding insertion means provided onto the bottom of the boardguides. Each crosspiece is supplied with grooves for being fixed to the sides and with a groove for snap insertion with the boardguides.
2. Description of the Related Art
The importance of subracks in the telecommunication systems is well known; they must allow the maximum number of printed circuit boards to be housed in the least possible volume, while at the same time meeting international standards such as DIN 41494-IEC 297.
Also well known is the continuous tendency to miniaturize electronic circuits, that is often at least partially offset by the lack of timely and suitable modifications of the mechanical structures that must house them.
In practice, subracks are typically formed up of four crosspieces that are redundantly supplied with drillings.
A second drawback added to this first drawback, arises from the fact that the pitch of the drillings is 5 08 mm, consequently the minimum pitch of the housing of printed circuits is made, in accordance with the standard DIN 41494-IEC 297, as a multiple of 5.08 (1/5 inch).
This minimum pitch is too low for telecommunication equipment (usually in continuous development), as it requires making unit dimensions that are multiple of 5.08 (e.g. 20.32, 25.4, 30.48, etc.).